UWSH CH 17 Flashcards
What is a Crack
A linear rupture of material under stress. Cracks may form anywhere on a surface, but are usually found near an edge or joint. Cracks have depth, length, and width and are not simply a surface defect.
What is a Dent?
A hollow area made by a blow or collision. There is no loss of material with a dent.
What is a Gouge?
A scooped out, shallow area or groove in the material caused by contact or collision with a hard object. This is common on softer material such as sonar dome
What is a Scratch?
A narrow surface defect that can be felt, but which has no depth into the material. Typically, scratches can be buffed out.
What is a Surface indication?
Any inconsistency of the surface that looks like a scratch or “hair line
crack” but cannot be felt or buffed out.
What is a Tear?
Pulled apart or separated by force, common on the leading edge of a bilge keel or a sonar dome rubber window.
What is a Delamination?
Separation between layers, common on shaft coatings and sonar domes. Delamination’s may be obvious with entire sections of material lost or may be hidden as a subsurface failure. Subsurface delamination’s may appear as bulges.
What is a Discontinuity?
Any imperfection (e.g., surface indication or crack) in the material that has been confirmed with an approved non-destructive test procedure using qualified personnel.
